Early spring annuals brighten up the yard
Plant cool season annuals in early-to-mid April, such as pansies and primulas, that can tolerate a light frost to add color to your garden. The Chicago Botanic Garden has begun installing the spring annuals display.
Temperatures that drop into the low 20s Fahrenheit can damage even the more cold-tolerant annuals, such as pansies; fortunately, none of these low temperatures are in the near-term forecast. Temperatures that go down to 25 degrees will likely damage the flowers on pansies. However, the plants should survive but their spring flower display will be severely impacted.
These early spring annuals can be planted under bulbs to complement their flowers and extend color until summer annuals are planted in mid-to-late May. Choose plants that are well developed with lots of flowers and buds.
The cool-season annuals do not have much time to develop after planting. If an exceptionally cold night with temperatures below 28 degrees is predicted, then it would be a good idea to cover your early spring annuals.
• There are a few evergreens showing winter burn or yellowing this spring. Some plants may be completely dead or beyond saving, while others will grow out this year.
Yews tend to be resilient. Look for new buds starting to grow; this will be a good sign your evergreen will recover. If a large percentage of the stems are dead and no new growth is starting, then you may have lost the plant.
Give the plants more time, as it is still early in spring, if you are unsure as to whether the plant is going to be OK. The extent of the damage and how long you are willing to wait for the plant to recover factor into making a decision to remove or not. Prune out any brown sections once you can be sure the stems are dead.
• It is getting to be the time to begin spraying crabapples that are susceptible to apple scab (typically this disease affects older varieties of crabs). If your tree's leaves become covered with black spots and fall off in late summer, it is in need of a protective spray program or should be replaced with a new disease resistant cultivar.
Begin spraying after the buds open and treat once every seven to ten days until the leaves are fully open (generally three treatments suffice). Contact the Chicago Botanic Garden's Plant Information Service, plantinfo@chicagobotanic.org, for recommended fungicides and timing for applications.
• Install bare root plant material as soon as you can after it arrives in the mail. Unpack plants and make sure the packing around the roots is moist. Store the plants in a cool place that will not freeze until they can be planted. It is a good idea to soak the roots of trees and shrubs in water for a short period of time before planting. Do not let the roots dry out. Prune only broken branches and roots before planting. There is no need to prune to compensate for transplant shock.
• Apply crab grass control if needed to lawns in early to mid-April, before weeds germinate. The window is later this year due to the cold spring. Complete this work before lilacs begin to flower. If you did not have problems with crab grass last year, then you should not need to apply crab grass control this year.
• Tim Johnson is director of horticulture at Chicago Botanic Garden, chicagobotanic.org.